Ceramic reed relay having flux carrying means associated with the armature



June 11, 1968 E. R. MYATT ETAL 3,388,355

CERAMIC REED RELAY HAVING FLUX CARRYING MEANS ASSOCIATED WITH THEARMATURE Fued Aug 1, 1966 3 Sheets-Sheet 1 June 11, 1968 E. R. MYATTETAL 3,383,355

CERAMIC REED RELAY HAVING FLUX CARRYING MEANS ASSOCIATED WITH THEARMATURE Filed Aug. 1, 1966 3 Sheets-Sheet 2 June 11, 1968 R TT T3,388,355

' CERAMIC REED RELAY HAVING FLUX CARRYING MEANS ASSOCIATED WITH THEARMATURE Flled Aug 1, 1966 3 Sheets-Sheet 5 United States Patent3,388,355 CERAMIC REED RELAY HAVING FLUX CAR- RYING MEANS ASSOCIATEDWITH THE ARMATURE Edward Ronald Myatt, Redbonrn, and Ernest FrederickLoveland, London, England, assignors to International Standard ElectricCorporation, New York, N.Y., a corporation of Delaware Filed Aug. 1,1966, Ser. No. 569,176 Claims priority, application Great Britain, July30, 1965, 32,743/ 65 14 (Ilaims. (Cl. 335-151) The invention relates toelectromagnetic relays of the kind having their contact making membershermetically sealed inside an enclosure and especially to relays havinga flat armature employed as a contact member.

According to the invention there is provided a sealed contact assemblyhaving two members of ferromagnetic material, which members are spacedapart and project into a sealed enclosure of electrically insulatingmaterial, each of the members having a contact carrying portion, whichmembers overlap each other at least over their respective contactcarrying portions, said assembly thereby having a fixed contact providedby one of said members, and an armature provided by the other one ofsaid members, the application of flux to said members causing saidarmature to engage with said fixed contact, and including fiux carryingmeans associated with said armature for increasing the effective flux inthe air gap between the armature and said fixed contact.

Embodiments of the invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 is a sectional side elevation of a contact assembly;

FIGS. 2A and 2B show an armature and a flux carrying member associatedtherewith, according to the invention, which are incorporated in acontact assembly of the type shown in FIG. 1;

FIGS. 3A and 3B are respectively a plan view of a rectangular plate andarmature, and a sectional side elevation of a contact assemblyincorporating the armature;

FIG. 4 is a side view of a modified armature arangement, according tothe invention, and an associated fixed contact;

FIG. 5 is a sectional side elevation of a double-make contact assembly;

FIG. 6 is a sectional end elevation of two double-make contactassemblies;

A FIG. 7 is a side view of a further contact assembly; FIG. 8 is a sideelevation of a change-over contact; FIGS. 9A to 9C show differentcontact arrangement which incorporates armature backstops;

FIGS. 10A to 10C show respectively a plan view, side elevation and endelevation of a modified armature and associated fixed contact;

FIGS. 11A and 1113 show the armature arrangement of FIG. 4 applied totwo further contact arrangements.

Referring to FIG. 1, a contact assembly has an annular plate 1 offerromagnetic material with an armature 2 formed from an integral withthe plate. The armature 2 has a portion at its unconnected end acting asa movable contact member. The plate 1 is sandwiched between two caps 3and 4 of electrically insulating material. A ferromagnetic rod 5 has oneend 6 extending through the end cap 4 to provide a fixed contact andmagnetic pole piece. The contacts are hermetically sealed inside theenclosure formed by the internal recesses of the end caps 3 and 4. Foroperating the contacts an energizing coil (not shown) can be wound roundthe rod 5, with electrical connection made to the contacts via the rod 5and upstanding portion of the plate 1. The end caps 3 and 4 arepreferably made ice of a ceramic material as also in the embodiment tobe described with reference to FIGS. 4, 5 and 6.

Where it is important that the contact assembly should be as small aspossible it is difficult to give an armature a sufiiciently high degreeof flexibility not to adversely affect the operating characteristics ofthe assembly.

FIGS. 2A and 2B show a short linear armature 2 whose flexibility isenhanced by reducing its cross-sectional area in the region of its fixedend. The armature is reduced in thickness over a portion of its lengthindicated by the hatched lines to produce a groove 12 across its width.An annular member 13 of ferromagnetic material of low reluctance isplaced against one side of the plate preferably the grooved side. Themember 13 is shaped to overlap at 14 the grooved portion of the armatureand is spaced from it. The member 13 compensates for the restriction tothe fiux path due to the groove 12.

FIGS. 3A and 3B show a contact assembly having a rectangular plate 23 offerromagnetic material hermetically sealed between two caps 24 and 25.The caps form an enclosure for an armature 26 and a fixed contact 27 onthe end of a ferromagnetic rod 28 hermetically sealed into the cap 25.In this arrangement the armature 26 is parallel to the longer sides ofthe diaphragm and is as long as is conveniently possible. Thus thelength of the armature is about equal to the longer dimension of thediaphragm.

Increased flux in the gap between the fixed contact member and theadjacent portion of the armature is obtained in the manner illustratedin FIG. 4 in which a member 29 of magnetic material is secured to thefixed end of the armature 26 and extends its length to overlap thearmature at its free end. ahe member 29 provides a further path for theflux leaving the contact carrying portion of the armature.

FIG. 5 shows an assembly having two make contacts. A further rectangularplate 30 of ferromagnetic material is spaced from the plate 23 by aspacer 31 of electrically insulating material. Integral with thediaphragm 30 is an armature 32 having a contact portion at its free endaligned with a fixed contact 33 carried on a rod 34 hermetically sealedinto the cap 24. If several assemblies each having two make contacts arearranged side by side to form a multiple contact device then, as shownin FIG. 6, the spacer 31 can be made common to all the assemblies. Thespacer 30 in the constructions as shown in both FIGS. 5 and 6 is made offerrite so as to increase the effective flux in the gap between thefixed contact members and the adjacent portion of the associatedarmatures, and so perform the function of the member 29 shown in FIG. 4.

As another alternative to the member 29, one of the end caps of theenclosure can be utilized for the purpose. The assembly illustrated inFIG. 7 has a ceramic end cap 38 and an end cap 39 of ferrite materialwhich is electrically insulating. The end cap 39 could be made of aconductive ferromagnetic material which would then be spaced from theplate by a spacer member of electrically insulating material.

As illustrated in FIG. 8, the rectangular plate type contact assemblycan be modified to operate as a change-over contact. A rectangular plate43 is sandwiched between two ceramic end caps 44 and 45. The armature 46is normally urged against a contact member 47 of non-magnetic material.The application of magnetic flux to the assembly attracts the armature46 to a second contact member 48 of ferromagnetic material. In order toensure that the armature is urged against the member 47 with therequired contact pressure, the contact bearing end of the member 47 isset to protrude beyond the plate contacting face of the cap 4-4 by adistance d, which is the amount by which the end of the armature 46 mustbe displaced to exert the required contact pressure against the member47. The end of the member 48 is set short of the diaphragm contactingface of the cap 45 by a distance of d+g Where g is the required distancebetween the armature and the member 48 when the armature is in its restposition. Therefore, when the plate and caps are secured together, thearmature is initially displaced by the member 47 towards the member 48 adistance equal to d and thus in its rest position remaining a distance gfrom the end of the member 48. To improve the Operating sensitivity inthe manner previously described with reference to FIG. 7, the cap 44could be made of either ferrite or ferromagnetic material. In the lattercase, however, it would be necessary to electrically insulate the platefrom the cap 44 by a spacer member of electrically insulating material.

In the case of the previously described single and double plateassemblies a back stop can be provided which is engaged by the armatureon its return to its rest position to shorten the period during whichthe armature vibrates before coming to rest. FIGS. 9A to 9C illustratevarious of the previously described constructions with a back stopprovided. FIG. 9A has a ferrite cap 49 which has a back-stop in the formof a stud 50 which is secured to the recessed face of the cap. In thereleased position the armature 51 rests against the stud 50. Theassembly of FIG. 98 has a ferromagnetic cap 52 which is provided with anindent 53 which serves as the back stop for the armature 54. Theassembly of FIG. 9C has two plates 55 and 56 separated by a ferritespacer 57. In this case the back-stops are in the form of studs 53 and59 which are located on opposite sides of the spacer 57. In each of theconstructions just described, the back-stop protrudes towards itsarmature sufliciently far for the armature to normally occupy a positionnearer to the fixed contact than would otherwise be the case.

To reduce the likelihood of faulty operation of the contact assembly dueto the contacts making poor electrical contact with each other, thearmatures of the previously described plates and their respective fixedcontacts may be modified as illustrated in FIGS. A to 10C by providing acylindrical end 60 to the fixed contact and a slot 61 in the free end ofthe armature. The end of the fixed contact has the axis of itscylindrical end across the width of the armature. When the contactsclose the two portions 62 and 63 of the armature on either side of theslot '61 are attracted independently of the armature makes poor contactthere is a good possibility that a low resistance make between its otherportion and the fixed contact will exist.

The features which have been described above relating to an improvementin the flexibility of the relay armature and to the provision ofadditional flux carrying means associated with the armature are notintended to be confined to contact assemblies having rectangulardiaphragms nor necessarily to assemblies of the construction illustratedin FIG. 1. In general these features are applicable to contact units ofthe type in which at least two socalled reeds are sealed into anenclosure of insulating material, e.g., glass, which is evacuated orfilled with an inert gas. One or both of the reed contacts is or are offerromagnetic material so that the application of magnetic flux theretocauses contact operation. FIGS. 11A and 11B illustrate two typicalsealed contact units of the type just described in which a movablemember 70 is reduced 'in thickness at its contact bearing end 71 forenhancing its flexibility. A magnetic member 72 is secured to the member70 at its fixed end either inside or outside the enclosure 73. Themember 72 serves the same purpose previously described for the member 29of FIG. 4.

It is to be understood that the foregoing description of specificexamples of this invention are made by way of example only and are notto be considered as a limitation on its scope.

What is claimed is:

1. A sealed contact assembly having two members of ferromagnetirmaterial, which members are spaced apart and project into a sealedenclosure of electrically insulating material, each of the membershaving a contact making portion, which members overlap each other atleast over their respective contact making portions, said assemblyhaving a fixed contact provided by one of said members and an armatureprovided by the other one of said members, the application of flux tosaid members causing said armature to engage with said fixed contact,flux carrying means associated with said armature for increasing theeffective flux in the air gap between the armature and said fixedcontact, said member forming said armature being a strip-like memberwhich is reduced in thickness over a portion of its length including itscontact carrying portion, and including a member of ferromagneticmaterial secured to the armature member between its fixed end and theportion of reduced thickness, which member extends parallel to saidarmature at least to a point opposite said fixed contact, which memberis spaced from said armature over a substantial portion of its length,wherein said member provides a further flux path between the contactbearing portion of said armature and the fixed end of said armature forincreasing the effective fiux in the air gap between the armature andsaid fixed contact.

2. A sealed contact assembly for a light current electromagnetic relayincluding a first member of ferromagnetic material in the form of a fiatannulus having a tongue-like armature formed from and inwardlyprojecting therefrom to provide a movable contact member, the fixed endof the armature having a portion of reduced thickness, a second memberof ferromagnetic material of low reluctance in the form of an annulusdimensionally similar to said first member, which second member has aninwardly projecting portion overlapping and spaced from the portion ofthe armature of reduced thickness, a cap of electrically insulatingmaterial sealed on each side of said first and second members to formtherewith a hermetically sealed enclosure between the caps, the interiorsurface of at least one of the caps being spaced from said armature toallow for its movement, and a rod of ferromagnetic material hermeticallysealed through the last mentioned cap to provide a fixed contact memberand magnetic pole piece co-operating with the movable contact member.

3. A sealed contact-assembly for a light current electromagnetic relayincluding a flat rectangular plate of ferromagnetic material, anarmature formed from and integral with said plate, a cap of electricallyinsulating material sealed on each side of said diaphragm to formtherewith a hermetically sealed enclosure between the caps, the interiorsurface of at least one of the caps being spaced from said armature toallow for its movement, and a rod of ferromagnetic material hermeticallysealed through the last mentioned cap to provide a fixed contact memberand magnetic pole piece co-operating with the movable contact member,and including flux carrying means carried by said armature forincreasing the effective flux in the air gap between the armature andsaid fixed contact.

4. An assembly as claimed in claim 3, in which the armature extends inthe direction of the longer pair of sides of the rectangular plate andis at least almost equal to the length of said sides.

5. An assembly as claimed in claim 3, in which the cap retaining thefixed contact member is of ceramic material, and the opposite cap is offerromagnetic material which provides said flux carrying means carriedby said armature.

6. An assembly as claimed in claim 3 and including a further fixedcontact member of non-magnetic material hermetically sealed through theopposite cap to that which carries said rod of ferromagnetic material,the interior surface of both said caps being spaced from said armatureto allow for its movement, said armature being normally spring urgedinto contact with said further fixed contact member and in which saidopposite cap is of ferromagnetic material which provides said fluxcarrying means associated with said armature.

7. An assembly as claimed in claim 5, wherein said opposite cap is offerrite material.

8. An assembly as claimed in claim 5, wherein said opposite cap is ofconductive ferromagnetic material, which cap is spaced from said plateby a spacer member of electrically insulating material.

9. An assembly as claimed in claim 3 including a further rectangularplate of ferromagnetic material dimensionally similar to the firstmentioned plate, the two plates being arranged parallel to each otherand spaced apart by a member of ferrite material, each plate havingsealed to one side thereof a different one of said caps, both capshaving an internal surface spaced from the adjacent armature, and afurther rod of ferromagnetic material hermetically sealed through theopposite cap to said last mentioned cap to provide a fixed contactmember and magnetic pole piece co-operating with the movable contactmember of the further plate, wherein the member of ferrite materialprovides said flux carrying means associated with each armature.

10. An assembly as claimed in claim 9, wherein the plates are arrangedwith their movable contact members common to one end of said enclosure.

11. At least two assemblies as claimed in claim 9 arranged side by sidewherein said member of ferrite ma terial is common to each of saidassemblies.

12. An assembly as claimed in claim 5 wherein said opposite cap isprovided with a back-stop for said armature, which stop is engaged bythe unconnected end of said armature when the armature occupies itsreleased position.

13. An assembly as claimed in claim 9, wherein said member of ferritematerial is provided with a back-stop for each said armature, whichstops are provided on o'p posite sides of the member, each of whichstops is engaged by the unconnected end of the associated armature whensaid armature occupies its released position.

14. At least one assembly as claimed in claim 2, wherein each saidarmature is provided with a slit parallel to the sides of the armatureand extending from its unconnected end, and wherein the fixed contactassociated with said armature has a cylindrical end thereto whose axisis arranged across the width of said armature.

References Cited FOREIGN PATENTS 2/ 1966 Great Britain. 4/1966 GreatBritain.

1. A SEALED CONTACT ASSEMBLY HAVING TWO MEMBERS OF FERROMAGNETICMATERIAL, WHICH MEMBERS ARE SPACED APART AND PROJECT INTO A SEALEDENCLOSURE OF ELECTRICALLY INSULATING MATERIAL, EACH OF THE MEMBERSHAVING A CONTACT MAKING PORTION, WHICH MEMBERS OVERLAP EACH OTHER ATLEAST OVER THEIR RESPECTIVE CONTACT MAKING PORTIONS, SAID ASSEMBLYHAVING A FIXED CONTACT PROVIDED BY ONE OF SAID MEMBERS AND AN ARMATUREPROVIDED BY THE OTHER ONE OF SAID MEMBERS, THE APPLICATION OF FLUX TOSAID MEMBERS CAUSING SAID ARMATURE TO ENGAGE WITH SAID FIXED CONTACT,FLUX CARRYING MEANS ASSOCIATED WITH SAID ARMATURE FOR INCREASING THEEFFECTIVE FLUX IN THE AIR GAP BETWEEN THE ARMATURE AND SAID FIXEDCONTACT, SAID MEMBER FORMING SAID ARMATURE BEING A STRIP-LIKE MEMBERWHICH IS REDUCED IN THICKNESS OVER A PORTION OF ITS LENGTH INCLUDING ITSCONTACT CARRYING PORTION, AND INCLUDING A MEMBER OF FERROMAGNETICMATERIAL SECURED TO THE ARMATURE MEMBER BETWEEN ITS FIXED END AND THEPORTION OF REDUCED THICKNESS, WHICH MEMBER EXTENDS PARALLEL TO SAIDARMATURE AT LEAST TO A POINT OPPOSITE SAID FIXED CONTACT, WHICH MEMBERIS SPACED FROM SAID ARMATURE OVER A SUBSTANTIAL PORTION OF ITS LENGTH,WHEREIN SAID MEMBER PROVIDES A FURTHER FLUX PATH BETWEEN THE CONTACTBEARING PORTION OF SAID ARMATURE AND THE FIXED END OF SAID ARMATURE FORINCREASING THE EFFECTIVE FLUX IN THE AIR GAP BETWEEN THE ARMATURE ANDSAID FIXED CONTACT.